1. Field of the Invention
The present invention relates to a liquid discharging head discharging a liquid and a producing method thereof as an aspect of the invention. To put it concretely, the present invention relates to an ink jet recording head performing recording by discharging an ink onto a recording medium and a producing method of the head.
Moreover, the present invention also relates to a minute structure and a producing method thereof as another aspect.
2. Description of the Related Art
As an example of using a liquid discharging head discharging a liquid, an ink jet recording system performing recording by discharging an ink to a recording medium can be cited.
An ink jet recording head to be applied to the ink jet recording system (liquid jet recording system) is generally equipped with a plurality of minute discharge ports, liquid flow paths, and energy generating devices provided at parts of the liquid flow paths to generate energy to be used for discharging a liquid. Conventionally, as a producing method of such an ink jet recording head, for example, U.S. Pat. No. 5,478,606 has disclosed the following.
First, a pattern of an ink flow path is formed on a substrate on which energy generating devices are formed by means of a resoluble resin. Next, a coating resin layer including an epoxy resin and a cationic photoinitiator is formed on the ink flow path pattern as an ink flow path wall, and discharge ports are formed on the energy generating devices by photolithography. The resoluble resin is finally eluted, and the coating resin layer to become the ink flow path wall is cured.
Now, it is necessary to consider the following at the time of the exposure of forming the pattern of the ink flow path and the discharge ports by the photolithography.
If a light is radiated from the discharge side, then the intensity of the lights radiated from the discharge ports to the substrate is attenuated because the member to be formed as the ink flow path walls absorbs light. Accordingly, in order to secure the joining property of the substrate with the ink flow path walls, it is necessary to radiate the light from the so-called discharge port surface situated in the vicinity of the substrate surface to a deeper position. Hereby, the member (epoxy resin or the like) to be formed as the ink flow path walls can sufficiently be cured at the deeper position mentioned above, and the ink resistance property thereof and the joining property thereof to the substrate can be obtained. On the other hand, it is necessary to consider the following in the case of radiating the light having the intensity of the degree of reaching from the discharge ports to the substrate surface in that manner to the member to be formed as the ink flow path walls. That is, if the light to be radiated has experienced the above-mentioned attenuation, then, even if the light is the one having an appropriate intensity in the vicinity of the substrate surface, the light sometimes is the one having an excessive intensity in the vicinity of the discharge ports where the light has not experienced any attenuation. If the light having the excessive intensity is radiated, then the light sometimes becomes an obstacle of obtaining the desired discharge ports with good accuracy. That is, there are apprehensions of the occurrences of the bad patterns of the discharge ports and the damage of the ink flow path pattern in the case of the producing method using the ink flow path mentioned above by the excessive exposure. If the failures mentioned above have occurred, the failures sometimes cause the dispersion of the directions and the sizes of discharged droplets, and the influences to the images are apprehended. Moreover, the discharge droplets of an ink jet recording head have recently tended to be miniaturized. Consequently, the dispersion of the directions and the sizes of the discharge droplets are more remarkable.